TY - JOUR
T1 - Bend, stretch, and touch: Locating a finger on an actively deformed transparent sensor array
JF - Science Advances
JO - Sci Adv
DO - 10.1126/sciadv.1602200
VL - 3
IS - 3
SP - e1602200
AU - Sarwar, Mirza Saquib
AU - Dobashi, Yuta
AU - Preston, Claire
AU - Wyss, Justin K. M.
AU - Mirabbasi, Shahriar
AU - Madden, John David Wyndham
Y1 - 2017/03/01
UR - http://advances.sciencemag.org/content/3/3/e1602200.abstract
N2 - The development of bendable, stretchable, and transparent touch sensors is an emerging technological goal in a variety of fields, including electronic skin, wearables, and flexible handheld devices. Although transparent tactile sensors based on metal mesh, carbon nanotubes, and silver nanowires demonstrate operation in bent configurations, we present a technology that extends the operation modes to the sensing of finger proximity including light touch during active bending and even stretching. This is accomplished using stretchable and ionically conductive hydrogel electrodes, which project electric field above the sensor to couple with and sense a finger. The polyacrylamide electrodes are embedded in silicone. These two widely available, low-cost, transparent materials are combined in a three-step manufacturing technique that is amenable to large-area fabrication. The approach is demonstrated using a proof-of-concept 4 × 4 cross-grid sensor array with a 5-mm pitch. The approach of a finger hovering a few centimeters above the array is readily detectable. Light touch produces a localized decrease in capacitance of 15%. The movement of a finger can be followed across the array, and the location of multiple fingers can be detected. Touch is detectable during bending and stretch, an important feature of any wearable device. The capacitive sensor design can be made more or less sensitive to bending by shifting it relative to the neutral axis. Ultimately, the approach is adaptable to the detection of proximity, touch, pressure, and even the conformation of the sensor surface.
ER -